A Systematic Method for Reducing Surfactant Retention to Extremely Low Levels

Abstract

The chemical cost to recover an incremental barrel of oil is directly proportional to the surfactant retention, so the single most effective way to reduce the cost is to reduce surfactant retention. The main objective of this research was to demonstrate how surfactant retention could be reduced to almost zero by careful optimization of the chemical formulations for different crude oils. Although surfactant retention has been studied for many years over a wide range of reservoir conditions, its dependence on the rheological behavior of the microemulsion that forms in-situ has not been adequately studied. Thus, in this paper we emphasize the importance of microemulsion rheology and demonstrate how to develop and test formulations with properties that give very low surfactant retention. Novel co-solvents (iso-butanol (IBA) alkoxylates and phenol alkoxylates) were tested in some of the formulations with excellent results. Unlike classical co-solvents used to optimize chemical formulations, the new co-solvents cause only a slight increase in the interfacial tension. A series of ASP corefloods were performed in sandstone cores with and without oil to measure surfactant and co-solvent retention and to elucidate the effects of microemulsion viscosity, salinity gradient, clay content, surfactant concentration and other variables. Dynamic adsorption was measured in cores with the same mineralogy and compared with the retention from oil recovery corefloods to determine the component of the retention due to phase trapping.

Evaluation of Surface-Active Ionic Liquids in Smart Water for Enhanced Oil Recovery in Carbonate Rocks

“…The purpose was to ensure that microemulsion Winsor type I (oil in water) was kept when the temperature increased from 50 to 130 °C. Since polar interactions between water molecules and ionic surfactant head groups can be reduced by the aqueous phase salinity, the partition of surfactant to the oil phase can be induced, and a shift of microemulsion from Winsor I to Winsor II could take place. ,− Winsor II, water in oil emulsion, means loss of formulation efficiency due to the increase of both SAIL retention and oil viscosity. − On the other hand, rising temperatures provoke stronger interactions between ionic surfactant head groups and water molecules, making them more hydrophilic as the temperature increases. ,− Figure presents the results of the phase behavior study of the SAIL formulations at 130 °C. The evaluated SAILs behaved highly hydrophilic during the test, showing microemulsion Winsor type I in the tested temperature interval and at the highest evaluated salinity (VB0S).…”

Comprehensive Review on the Role of Surfactants in the Chemical Enhanced Oil Recovery Process

“…However, it does not yield appreciable results while using it with anionic surfactants owing to the phase trapping. 150 Alteration of interfacial rheology by injecting highly dispersed nanoemulsions and microemulsions has also proven to be a cure for surfactant loss. 342−344 Recent studies in surfactant-aided cEOR techniques have seen progress in surfactant polymers that are independent alkali systems, applications of nanotechnology to enhance surfactant flooding efficiencies, deeper investigation into the molecular structure of surfactant to understand rock−fluid−surfactant interactions, and advances in extraction of stable natural biodegradable surfactants and smart surfactant encapsulation that trigger release at specific conditions during the cEOR processes.…”

“…Hence, researchers have examined alternatives like sodium polyacrylate, di-isopropyl amine (with 10 units of ethylene oxide), sodium tetraborate, and sodium metaborate to reduce retention of surfactants, especially in carbonate reservoirs. ,,, Recent advances in chelating agents containing different functional groups have contributed to addressing these problems by seizing multivalent cations and by forming a stable complex. , The use of CO 2 along with a cationic surfactant to minimize adsorption on carbonate formations has also led to recent breakthroughs. However, it does not yield appreciable results while using it with anionic surfactants owing to the phase trapping . Alteration of interfacial rheology by injecting highly dispersed nanoemulsions and microemulsions has also proven to be a cure for surfactant loss. − Recent studies in surfactant-aided cEOR techniques have seen progress in surfactant polymers that are independent alkali systems, applications of nanotechnology to enhance surfactant flooding efficiencies, deeper investigation into the molecular structure of surfactant to understand rock–fluid–surfactant interactions, and advances in extraction of stable natural biodegradable surfactants and smart surfactant encapsulation that trigger release at specific conditions during the cEOR processes.…”